<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source to the Rust file `/home/mrh/.cargo/registry/src/github.com-1ecc6299db9ec823/image-0.21.2/./src/pnm/header.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>header.rs.html -- source</title><link rel="stylesheet" type="text/css" href="../../../normalize.css"><link rel="stylesheet" type="text/css" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../../dark.css"><link rel="stylesheet" type="text/css" href="../../../light.css" id="themeStyle"><script src="../../../storage.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="shortcut icon" href="../../../favicon.ico"><style type="text/css">#crate-search{background-image:url("../../../down-arrow.svg");}</style></head><body class="rustdoc source"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../../image/index.html'><div class='logo-container'><img src='../../../rust-logo.png' alt='logo'></div></a></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../../../settings.html"><img src="../../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><div class="example-wrap"><pre class="rust ">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>;
<span class="doccomment">/// The kind of encoding used to store sample values</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">SampleEncoding</span> {
<span class="doccomment">/// Samples are unsigned binary integers in big endian</span>
<span class="ident">Binary</span>,
<span class="doccomment">/// Samples are encoded as decimal ascii strings separated by whitespace</span>
<span class="ident">Ascii</span>,
}
<span class="doccomment">/// Denotes the category of the magic number</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">PNMSubtype</span> {
<span class="doccomment">/// Magic numbers P1 and P4</span>
<span class="ident">Bitmap</span>(<span class="ident">SampleEncoding</span>),
<span class="doccomment">/// Magic numbers P2 and P5</span>
<span class="ident">Graymap</span>(<span class="ident">SampleEncoding</span>),
<span class="doccomment">/// Magic numbers P3 and P6</span>
<span class="ident">Pixmap</span>(<span class="ident">SampleEncoding</span>),
<span class="doccomment">/// Magic number P7</span>
<span class="ident">ArbitraryMap</span>,
}
<span class="doccomment">/// Stores the complete header data of a file.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Internally, provides mechanisms for lossless reencoding. After reading a file with the decoder</span>
<span class="doccomment">/// it is possible to recover the header and construct an encoder. Using the encoder on the just</span>
<span class="doccomment">/// loaded image should result in a byte copy of the original file (for single image pnms without</span>
<span class="doccomment">/// additional trailing data).</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">PNMHeader</span> {
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="ident">decoded</span>: <span class="ident">HeaderRecord</span>,
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="ident">encoded</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span>,
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">enum</span> <span class="ident">HeaderRecord</span> {
<span class="ident">Bitmap</span>(<span class="ident">BitmapHeader</span>),
<span class="ident">Graymap</span>(<span class="ident">GraymapHeader</span>),
<span class="ident">Pixmap</span>(<span class="ident">PixmapHeader</span>),
<span class="ident">Arbitrary</span>(<span class="ident">ArbitraryHeader</span>),
}
<span class="doccomment">/// Header produced by a `pbm` file ("Portable Bit Map")</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">BitmapHeader</span> {
<span class="doccomment">/// Binary or Ascii encoded file</span>
<span class="kw">pub</span> <span class="ident">encoding</span>: <span class="ident">SampleEncoding</span>,
<span class="doccomment">/// Height of the image file</span>
<span class="kw">pub</span> <span class="ident">height</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Width of the image file</span>
<span class="kw">pub</span> <span class="ident">width</span>: <span class="ident">u32</span>,
}
<span class="doccomment">/// Header produced by a `pgm` file ("Portable Gray Map")</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">GraymapHeader</span> {
<span class="doccomment">/// Binary or Ascii encoded file</span>
<span class="kw">pub</span> <span class="ident">encoding</span>: <span class="ident">SampleEncoding</span>,
<span class="doccomment">/// Height of the image file</span>
<span class="kw">pub</span> <span class="ident">height</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Width of the image file</span>
<span class="kw">pub</span> <span class="ident">width</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Maximum sample value within the image</span>
<span class="kw">pub</span> <span class="ident">maxwhite</span>: <span class="ident">u32</span>,
}
<span class="doccomment">/// Header produced by a `ppm` file ("Portable Pixel Map")</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">PixmapHeader</span> {
<span class="doccomment">/// Binary or Ascii encoded file</span>
<span class="kw">pub</span> <span class="ident">encoding</span>: <span class="ident">SampleEncoding</span>,
<span class="doccomment">/// Height of the image file</span>
<span class="kw">pub</span> <span class="ident">height</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Width of the image file</span>
<span class="kw">pub</span> <span class="ident">width</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Maximum sample value within the image</span>
<span class="kw">pub</span> <span class="ident">maxval</span>: <span class="ident">u32</span>,
}
<span class="doccomment">/// Header produced by a `pam` file ("Portable Arbitrary Map")</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">ArbitraryHeader</span> {
<span class="doccomment">/// Height of the image file</span>
<span class="kw">pub</span> <span class="ident">height</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Width of the image file</span>
<span class="kw">pub</span> <span class="ident">width</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Number of color channels</span>
<span class="kw">pub</span> <span class="ident">depth</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Maximum sample value within the image</span>
<span class="kw">pub</span> <span class="ident">maxval</span>: <span class="ident">u32</span>,
<span class="doccomment">/// Color interpretation of image pixels</span>
<span class="kw">pub</span> <span class="ident">tupltype</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">ArbitraryTuplType</span><span class="op">></span>,
}
<span class="doccomment">/// Standardized tuple type specifiers in the header of a `pam`.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">ArbitraryTuplType</span> {
<span class="doccomment">/// Pixels are either black (0) or white (1)</span>
<span class="ident">BlackAndWhite</span>,
<span class="doccomment">/// Pixels are either black (0) or white (1) and a second alpha channel</span>
<span class="ident">BlackAndWhiteAlpha</span>,
<span class="doccomment">/// Pixels represent the amount of white</span>
<span class="ident">Grayscale</span>,
<span class="doccomment">/// Grayscale with an additional alpha channel</span>
<span class="ident">GrayscaleAlpha</span>,
<span class="doccomment">/// Three channels: Red, Green, Blue</span>
<span class="ident">RGB</span>,
<span class="doccomment">/// Four channels: Red, Green, Blue, Alpha</span>
<span class="ident">RGBAlpha</span>,
<span class="doccomment">/// An image format which is not standardized</span>
<span class="ident">Custom</span>(<span class="ident">String</span>),
}
<span class="kw">impl</span> <span class="ident">PNMSubtype</span> {
<span class="doccomment">/// Get the two magic constant bytes corresponding to this format subtype.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">magic_constant</span>(<span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="kw-2">&</span><span class="lifetime">'static</span> [<span class="ident">u8</span>; <span class="number">2</span>] {
<span class="kw">match</span> <span class="self">self</span> {
<span class="ident">PNMSubtype</span>::<span class="ident">Bitmap</span>(<span class="ident">SampleEncoding</span>::<span class="ident">Ascii</span>) <span class="op">=</span><span class="op">></span> <span class="string">b"P1"</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Graymap</span>(<span class="ident">SampleEncoding</span>::<span class="ident">Ascii</span>) <span class="op">=</span><span class="op">></span> <span class="string">b"P2"</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Pixmap</span>(<span class="ident">SampleEncoding</span>::<span class="ident">Ascii</span>) <span class="op">=</span><span class="op">></span> <span class="string">b"P3"</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Bitmap</span>(<span class="ident">SampleEncoding</span>::<span class="ident">Binary</span>) <span class="op">=</span><span class="op">></span> <span class="string">b"P4"</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Graymap</span>(<span class="ident">SampleEncoding</span>::<span class="ident">Binary</span>) <span class="op">=</span><span class="op">></span> <span class="string">b"P5"</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Pixmap</span>(<span class="ident">SampleEncoding</span>::<span class="ident">Binary</span>) <span class="op">=</span><span class="op">></span> <span class="string">b"P6"</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">ArbitraryMap</span> <span class="op">=</span><span class="op">></span> <span class="string">b"P7"</span>,
}
}
<span class="doccomment">/// Whether samples are stored as binary or as decimal ascii</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">sample_encoding</span>(<span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">SampleEncoding</span> {
<span class="kw">match</span> <span class="self">self</span> {
<span class="ident">PNMSubtype</span>::<span class="ident">ArbitraryMap</span> <span class="op">=</span><span class="op">></span> <span class="ident">SampleEncoding</span>::<span class="ident">Binary</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Bitmap</span>(<span class="ident">enc</span>) <span class="op">=</span><span class="op">></span> <span class="ident">enc</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Graymap</span>(<span class="ident">enc</span>) <span class="op">=</span><span class="op">></span> <span class="ident">enc</span>,
<span class="ident">PNMSubtype</span>::<span class="ident">Pixmap</span>(<span class="ident">enc</span>) <span class="op">=</span><span class="op">></span> <span class="ident">enc</span>,
}
}
}
<span class="kw">impl</span> <span class="ident">PNMHeader</span> {
<span class="doccomment">/// Retrieve the format subtype from which the header was created.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">subtype</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">PNMSubtype</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Bitmap</span>(<span class="ident">BitmapHeader</span> { <span class="ident">encoding</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">PNMSubtype</span>::<span class="ident">Bitmap</span>(<span class="ident">encoding</span>),
<span class="ident">HeaderRecord</span>::<span class="ident">Graymap</span>(<span class="ident">GraymapHeader</span> { <span class="ident">encoding</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">PNMSubtype</span>::<span class="ident">Graymap</span>(<span class="ident">encoding</span>),
<span class="ident">HeaderRecord</span>::<span class="ident">Pixmap</span>(<span class="ident">PixmapHeader</span> { <span class="ident">encoding</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">PNMSubtype</span>::<span class="ident">Pixmap</span>(<span class="ident">encoding</span>),
<span class="ident">HeaderRecord</span>::<span class="ident">Arbitrary</span>(<span class="ident">ArbitraryHeader</span> { .. }) <span class="op">=</span><span class="op">></span> <span class="ident">PNMSubtype</span>::<span class="ident">ArbitraryMap</span>,
}
}
<span class="doccomment">/// The width of the image this header is for.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">width</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u32</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Bitmap</span>(<span class="ident">BitmapHeader</span> { <span class="ident">width</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">width</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Graymap</span>(<span class="ident">GraymapHeader</span> { <span class="ident">width</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">width</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Pixmap</span>(<span class="ident">PixmapHeader</span> { <span class="ident">width</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">width</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Arbitrary</span>(<span class="ident">ArbitraryHeader</span> { <span class="ident">width</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">width</span>,
}
}
<span class="doccomment">/// The height of the image this header is for.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">height</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u32</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Bitmap</span>(<span class="ident">BitmapHeader</span> { <span class="ident">height</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">height</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Graymap</span>(<span class="ident">GraymapHeader</span> { <span class="ident">height</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">height</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Pixmap</span>(<span class="ident">PixmapHeader</span> { <span class="ident">height</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">height</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Arbitrary</span>(<span class="ident">ArbitraryHeader</span> { <span class="ident">height</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">height</span>,
}
}
<span class="doccomment">/// The biggest value a sample can have. In other words, the colour resolution.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">maximal_sample</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u32</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Bitmap</span>(<span class="ident">BitmapHeader</span> { .. }) <span class="op">=</span><span class="op">></span> <span class="number">1</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Graymap</span>(<span class="ident">GraymapHeader</span> { <span class="ident">maxwhite</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">maxwhite</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Pixmap</span>(<span class="ident">PixmapHeader</span> { <span class="ident">maxval</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">maxval</span>,
<span class="ident">HeaderRecord</span>::<span class="ident">Arbitrary</span>(<span class="ident">ArbitraryHeader</span> { <span class="ident">maxval</span>, .. }) <span class="op">=</span><span class="op">></span> <span class="ident">maxval</span>,
}
}
<span class="doccomment">/// Retrieve the underlying bitmap header if any</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">as_bitmap</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">BitmapHeader</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Bitmap</span>(<span class="kw-2">ref</span> <span class="ident">bitmap</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Some</span>(<span class="ident">bitmap</span>),
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="prelude-val">None</span>,
}
}
<span class="doccomment">/// Retrieve the underlying graymap header if any</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">as_graymap</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">GraymapHeader</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Graymap</span>(<span class="kw-2">ref</span> <span class="ident">graymap</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Some</span>(<span class="ident">graymap</span>),
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="prelude-val">None</span>,
}
}
<span class="doccomment">/// Retrieve the underlying pixmap header if any</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">as_pixmap</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">PixmapHeader</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Pixmap</span>(<span class="kw-2">ref</span> <span class="ident">pixmap</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Some</span>(<span class="ident">pixmap</span>),
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="prelude-val">None</span>,
}
}
<span class="doccomment">/// Retrieve the underlying arbitrary header if any</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">as_arbitrary</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">ArbitraryHeader</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">decoded</span> {
<span class="ident">HeaderRecord</span>::<span class="ident">Arbitrary</span>(<span class="kw-2">ref</span> <span class="ident">arbitrary</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Some</span>(<span class="ident">arbitrary</span>),
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="prelude-val">None</span>,
}
}
<span class="doccomment">/// Write the header back into a binary stream</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">write</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">io</span>::<span class="ident">Write</span>) <span class="op">-</span><span class="op">></span> <span class="ident">io</span>::<span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="ident">writer</span>.<span class="ident">write_all</span>(<span class="self">self</span>.<span class="ident">subtype</span>().<span class="ident">magic_constant</span>())<span class="question-mark">?</span>;
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">PNMHeader</span> {
<span class="ident">encoded</span>: <span class="prelude-val">Some</span>(<span class="kw-2">ref</span> <span class="ident">content</span>),
..
} <span class="op">=</span><span class="op">></span> <span class="ident">writer</span>.<span class="ident">write_all</span>(<span class="ident">content</span>),
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>:
<span class="ident">HeaderRecord</span>::<span class="ident">Bitmap</span>(<span class="ident">BitmapHeader</span> {
<span class="ident">encoding</span>: <span class="ident">_encoding</span>,
<span class="ident">width</span>,
<span class="ident">height</span>,
}),
..
} <span class="op">=</span><span class="op">></span> <span class="macro">writeln</span><span class="macro">!</span>(<span class="ident">writer</span>, <span class="string">"\n{} {}"</span>, <span class="ident">width</span>, <span class="ident">height</span>),
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>:
<span class="ident">HeaderRecord</span>::<span class="ident">Graymap</span>(<span class="ident">GraymapHeader</span> {
<span class="ident">encoding</span>: <span class="ident">_encoding</span>,
<span class="ident">width</span>,
<span class="ident">height</span>,
<span class="ident">maxwhite</span>,
}),
..
} <span class="op">=</span><span class="op">></span> <span class="macro">writeln</span><span class="macro">!</span>(<span class="ident">writer</span>, <span class="string">"\n{} {} {}"</span>, <span class="ident">width</span>, <span class="ident">height</span>, <span class="ident">maxwhite</span>),
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>:
<span class="ident">HeaderRecord</span>::<span class="ident">Pixmap</span>(<span class="ident">PixmapHeader</span> {
<span class="ident">encoding</span>: <span class="ident">_encoding</span>,
<span class="ident">width</span>,
<span class="ident">height</span>,
<span class="ident">maxval</span>,
}),
..
} <span class="op">=</span><span class="op">></span> <span class="macro">writeln</span><span class="macro">!</span>(<span class="ident">writer</span>, <span class="string">"\n{} {} {}"</span>, <span class="ident">width</span>, <span class="ident">height</span>, <span class="ident">maxval</span>),
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>:
<span class="ident">HeaderRecord</span>::<span class="ident">Arbitrary</span>(<span class="ident">ArbitraryHeader</span> {
<span class="ident">width</span>,
<span class="ident">height</span>,
<span class="ident">depth</span>,
<span class="ident">maxval</span>,
<span class="kw-2">ref</span> <span class="ident">tupltype</span>,
}),
..
} <span class="op">=</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">allow</span>(<span class="ident">unused_assignments</span>)]</span>
<span class="comment">// Declared here so its lifetime exceeds the matching. This is a trivial</span>
<span class="comment">// constructor, no allocation takes place and in the custom case we must allocate</span>
<span class="comment">// regardless due to borrow. Still, the warnings checker does pick this up :/</span>
<span class="comment">// Could use std::borrow::Cow instead but that really doesn't achieve anything but</span>
<span class="comment">// increasing type complexity.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">custom_fallback</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">new</span>();
<span class="kw">let</span> <span class="ident">tupltype</span> <span class="op">=</span> <span class="kw">match</span> <span class="kw-2">*</span><span class="ident">tupltype</span> {
<span class="prelude-val">None</span> <span class="op">=</span><span class="op">></span> <span class="string">""</span>,
<span class="prelude-val">Some</span>(<span class="ident">ArbitraryTuplType</span>::<span class="ident">BlackAndWhite</span>) <span class="op">=</span><span class="op">></span> <span class="string">"TUPLTYPE BLACKANDWHITE\n"</span>,
<span class="prelude-val">Some</span>(<span class="ident">ArbitraryTuplType</span>::<span class="ident">BlackAndWhiteAlpha</span>) <span class="op">=</span><span class="op">></span> <span class="string">"TUPLTYPE BLACKANDWHITE_ALPHA\n"</span>,
<span class="prelude-val">Some</span>(<span class="ident">ArbitraryTuplType</span>::<span class="ident">Grayscale</span>) <span class="op">=</span><span class="op">></span> <span class="string">"TUPLTYPE GRAYSCALE\n"</span>,
<span class="prelude-val">Some</span>(<span class="ident">ArbitraryTuplType</span>::<span class="ident">GrayscaleAlpha</span>) <span class="op">=</span><span class="op">></span> <span class="string">"TUPLTYPE GRAYSCALE_ALPHA\n"</span>,
<span class="prelude-val">Some</span>(<span class="ident">ArbitraryTuplType</span>::<span class="ident">RGB</span>) <span class="op">=</span><span class="op">></span> <span class="string">"TUPLTYPE RGB\n"</span>,
<span class="prelude-val">Some</span>(<span class="ident">ArbitraryTuplType</span>::<span class="ident">RGBAlpha</span>) <span class="op">=</span><span class="op">></span> <span class="string">"TUPLTYPE RGB_ALPHA\n"</span>,
<span class="prelude-val">Some</span>(<span class="ident">ArbitraryTuplType</span>::<span class="ident">Custom</span>(<span class="kw-2">ref</span> <span class="ident">custom</span>)) <span class="op">=</span><span class="op">></span> {
<span class="ident">custom_fallback</span> <span class="op">=</span> <span class="macro">format</span><span class="macro">!</span>(<span class="string">"TUPLTYPE {}"</span>, <span class="ident">custom</span>);
<span class="kw-2">&</span><span class="ident">custom_fallback</span>
}
};
<span class="macro">writeln</span><span class="macro">!</span>(
<span class="ident">writer</span>,
<span class="string">"\nWIDTH {}\nHEIGHT {}\nDEPTH {}\nMAXVAL {}\n{}ENDHDR"</span>,
<span class="ident">width</span>, <span class="ident">height</span>, <span class="ident">depth</span>, <span class="ident">maxval</span>, <span class="ident">tupltype</span>
)
}
}
}
}
<span class="kw">impl</span> <span class="ident">From</span><span class="op"><</span><span class="ident">BitmapHeader</span><span class="op">></span> <span class="kw">for</span> <span class="ident">PNMHeader</span> {
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">header</span>: <span class="ident">BitmapHeader</span>) <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>: <span class="ident">HeaderRecord</span>::<span class="ident">Bitmap</span>(<span class="ident">header</span>),
<span class="ident">encoded</span>: <span class="prelude-val">None</span>,
}
}
}
<span class="kw">impl</span> <span class="ident">From</span><span class="op"><</span><span class="ident">GraymapHeader</span><span class="op">></span> <span class="kw">for</span> <span class="ident">PNMHeader</span> {
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">header</span>: <span class="ident">GraymapHeader</span>) <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>: <span class="ident">HeaderRecord</span>::<span class="ident">Graymap</span>(<span class="ident">header</span>),
<span class="ident">encoded</span>: <span class="prelude-val">None</span>,
}
}
}
<span class="kw">impl</span> <span class="ident">From</span><span class="op"><</span><span class="ident">PixmapHeader</span><span class="op">></span> <span class="kw">for</span> <span class="ident">PNMHeader</span> {
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">header</span>: <span class="ident">PixmapHeader</span>) <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>: <span class="ident">HeaderRecord</span>::<span class="ident">Pixmap</span>(<span class="ident">header</span>),
<span class="ident">encoded</span>: <span class="prelude-val">None</span>,
}
}
}
<span class="kw">impl</span> <span class="ident">From</span><span class="op"><</span><span class="ident">ArbitraryHeader</span><span class="op">></span> <span class="kw">for</span> <span class="ident">PNMHeader</span> {
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">header</span>: <span class="ident">ArbitraryHeader</span>) <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
<span class="ident">PNMHeader</span> {
<span class="ident">decoded</span>: <span class="ident">HeaderRecord</span>::<span class="ident">Arbitrary</span>(<span class="ident">header</span>),
<span class="ident">encoded</span>: <span class="prelude-val">None</span>,
}
}
}
</pre></div>
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